1. Field of the Invention
The present invention is related to precision journal bearings, and more specifically to a precision journal bearing intended to operate in, yet be protected from, highly abrasive and contaminated fluids.
2. State of the Prior Art
Fluid flow meters for measuring the rate of flow of fluids are often constructed with turbine-type rotors journaled in a frame and having curved or dynamically twisted, radially extending vanes that are driven by a flowing fluid. Since the rate of rotation of the rotor driven by the flowing fluid is desired to be as close to directly proportional to the rate of fluid flow as possible for accurate, useful flow rate measurements, the journal bearing has to have almost no friction or drag. Thus, seals or completely enclosed bearings are not practical. Yet, grit, particulate matter, and other contaminants in the flowing fluid can be extremely detrimental to open rotor bearings. For example, flow meter rotors that will function normally and without trouble for years in fluids that do not have particulate matter greater than about 25 microns and nominal concentrations in the range of about 125-1000 ppm will quit working in only a matter of several days when operating in particle laden fluids, such as coke slurries and the like.
Therefore, there is a significant need for a small, precision journal bearing structure for flow meter rotors that is not sealed, yet which can continue operating without disintegrating or jamming in fluids or slurries having high particulate concentrations and contaminants.